Search results for "MAX"
showing 10 items of 2447 documents
Summer air temperature, reconstructions from the last glacial stage based on rodents from the site Taillis-des-Coteaux (Vienne), Western France.
2014
AbstractThe oxygen isotope composition of phosphate from tooth enamel of rodents (δ18Op) constitutes a valuable proxy to reconstruct past air temperatures in continental environments. This method has been applied to rodent dental remains from three genera, Arvicola sp., Microtus sp. and Dicrostonyx sp., coming from Taillis-des-Coteaux, Vienne, France. This archaeological site contains an exceptionally preserved sedimentary sequence spanning almost the whole Upper Palaeolithic, including seven stratigraphic layers dated from 35 to 17 cal ka BP. The abundant presence of rodent remains offers the opportunity to quantify the climatic fluctuations coeval of the various stages of human occupation…
New tree-ring evidence for the Late Glacial period from the northern pre-Alps in eastern Switzerland
2018
Abstract The rate and magnitude of temperature variability at the transition from the Last Glacial Maximum into the early Holocene represents a natural analog to current and predicted climate change. A limited number of high-resolution proxy archives, however, challenges our understanding of environmental conditions during this period. Here, we present combined dendrochronological and radiocarbon evidence from 253 newly discovered subfossil pine stumps from Zurich, Switzerland. The individual trees reveal ages of 41–506 years and were growing between the Allerod and Preboreal (∼13′900–11′300 cal BP). Together with previously collected pines from this region, this world's best preserved Late…
Caribbean hydroclimate and vegetation history across the last glacial period
2019
Abstract We present a new speleothem trace element and stable isotope record, which extends previous paleoclimate evidence from Cuban speleothems to the last 96 ka. Multiple proxies were used to reconstruct Caribbean hydroclimate and vegetation variability on orbital to millennial timescales. In particular, our proxies indicate a shift to more abundant C4 (compared to C3) vegetation and/or reduced soil activity during the Last Glacial Maximum. Our results confirm the close link of Caribbean precipitation to North Atlantic climate variability, insolation and the strength of the AMOC. The associated variations in Caribbean SSTs and the shift of the ITCZ led to substantial changes of the hydro…
Human occupation and environmental change in the western Maghreb during the Last Glacial Maximum (LGM) and the Late Glacial. New evidence from the Ib…
2019
With the onset of the Last Glacial Maximum (LGM), hunter-gatherers of the so-called Iberomaurusian techno-complex appeared in what is now the Mediterranean Maghreb. During a period of about seven thousand years, these groups left sandy occupation layers in a limited number of archaeological sites, while at the beginning of Greenland Interstadial (GI) 1, the sudden shift towards the deposition of shell-rich sediments and the increase in number of sites document clear changes in subsistence strategies as well as occupation density. It is highly likely that these shifts in human behaviour are related to paleoenvironmental changes in the area, which, so far, are poorly documented in geological …
Paleogenetic and morphometric analysis of a Mesolithic individual from Grotta d'Oriente: An oldest genetic legacy for the first modern humans in Sici…
2020
Abstract Grotta d’Oriente, a coastal cave located on the island of Favignana (Sicily, Italy) is a key site for the study of the early human colonization of Sicily. Inside the cave, during different field excavations, three burials attributable to the Late Upper Palaeolithic and Mesolithic were found. The Mesolithic Oriente B individual, directly dated at 9,377 ± 25 uncal BP, was previously assigned to HV1 haplogroup using a traditional approach. However, it is well known that PCR based methods are prone to erroneous haplotype or haplogroup determination. In order to redefine the mitochondrial lineage of this Mesolithic hunter-gatherer and explore its phylogenetic position, we target-enriche…
Volcanic climate forcing preceding the inception of the Younger Dryas: Implications for tracing the Laacher See eruption
2021
Climatic warming from the last glacial maximum to the current interglacial period was punctuated by a similar to 1300 years long cold period, commonly referred to as the Younger Dryas (YD). Several hypotheses have been proposed for the mechanism triggering the abrupt inception of the YD, including freshwater forcing, an extra-terrestrial impact, and aerosols from volcanic eruptions. Here, we use synchronised sulphate and sulphur records from both Greenland and Antarctic ice cores to reconstruct volcanic forcing between 13,200-12,800 a BPGICC05 (years before 1950 CE on the Greenland Ice Core Chronology 2005; GICC05). This continuous reconstruction of stratospheric sulphur injections highligh…
Late Quaternary palaeoenvironmental reconstruction of sediment drift accumulation in the Malta Graben (central Mediterranean Sea)
2018
The Malta Graben is a deep tectonic depression in the Sicily Channel, bounded by NW-SE normal faults and filled by thick Pliocene-Quaternary deposits. A previous analysis of a giant piston core (LC09) from the Malta Graben had revealed a wide range of sedimentary features (carbonate turbidites, bioturbated mud and scours), although the chronostratigraphic constraint of the stacking pattern has remained elusive. After establishing a reliable chronological framework based on seven radiocarbon dates for a shorter core from the Malta Graben (ANSIC03-735), a down-core analysis of planktonic foraminifer and coccolith abundance, stable isotopes and sediment grain size was carried out. Since the la…
The Late Ordovician glacial sedimentary system of the North Gondwana platform.
2009
International audience; The Late Ordovician (Hirnantian) glaciation is examined through the North Gondwana record. This domain extended from southern high palaeo-latitudes (southeastern Mauritania, Niger) to northern lower palaeo-latitudes (Morocco, Turkey) and covered a more than 4000 km-wide section perpendicular to ice-flow lines. A major mid-Hirnantian deglaciation event subdividing the Hirnantian glaciation in two first-order cycles is recognised. As best illustrated by the glacial record in western Libya, each cycle comprises 2-3 glacial phases separated by ice-front retreats several hundreds kilometres to the south. From ice-proximal to ice-distal regions, the number of glacial surfa…
Five centuries of Central European temperature extremes reconstructed from tree-ring density and documentary evidence
2010
Future climate change will likely influence the frequency and intensity of weather extremes. As such events are by definition rare, long records are required to understand their characteristics, drivers, and consequences on ecology and society. Herein we provide a unique perspective on regional-scale temperature extremes over the past millennium, using three tree-ring maximum latewood density (MXD) chronologies from higher elevations in the European Alps. We verify the tree-ring-based extremes using documentary evidences from Switzerland, the Czech Republic, and Central Europe that allowed the identification of 44 summer extremes over the 1550-2003 period. These events include cold temperat…
Calcareous nannofossil palaeoenvironmental reconstruction and preservation in sapropel S1 at the Eratosthenes Seamount (Eastern Mediterranean)
2019
Abstract The most recent organic carbon-enriched layer (sapropel S1) deposited at the Eratosthenes Seamount has unique features, such as an early lithological interruption, fine light silt laminae and an exceptional vertical extent that is over 25 cm thick. Here we investigate calcareous nannofossil assemblages to reconstruct very high-resolution palaeoenvironmental and palaeoceanographic variations recorded before, during and after the perturbation episode that involved the eastern Mediterranean Sea, due to the massive freshwater discharge via Nile River. Our results show that the deep chlorophyll maximum development, observed in all micropalaeontological groups from previous studies, is a…